As an information display for outdoor installation, such as, for example, a CRT display using a cathode-ray tube and an LCD display using liquid crystal have been well-known. Especially, an LCD display is beginning to predominate as an information display since being thin and light-weight, having a broader range of installation conditions.
Such information displays are, for being installed in rough environments such as roads and trains, easy to allow, for example, suspended dust to intrude into the display device. Among such dust, metallic powder such as iron powder largely affects the device and often causes such as failures. Considering the foregoing, for example, the Patent Literature 1 has been known as a dust intrusion preventing technology for a display device.    [Patent Literature 1]: Japanese Unexamined Patent Publication No. 2007-86649